Finite Element Modelling of Laser Beam Machining For Titanium 5553 Alloy

Transcription

1 Finit Elmnt Modlling of Lasr Bam Machining For Titanium 5553 Alloy D. Vnkata Krishna 1, Aashish Mallik 2, Gansh Kharl 3, A. Kumara Swamy 4, E. Ranjith Kumar 5 Abstract Arospac industry has bn thriving for th past fw dcads and with passag of ach dcad w hav bn trying to achiv fastr and lightr spaccraft. On of th major filds of rsarch is th matrial bing usd. Supr alloys possssing high strngth to wight ratio, corrosion rsistanc and highr thrmal adhrnc hav bn undr scrutiny. Titanium alloy 5553 (Ti-5Al-5V-5Mo-3Cr) is a nar bta alloy with sublim hardnability and strngth charactristics and is a promising substitut for prsnt options. As th traditional mthods ar incomptnt to machin th supr alloys, a modrn machining procss such as lasr bam machining has bn suggstd. At prsnt work, a symmtrical work pic in suitabl dimnsions is modlld using 3D modlling. This modl is usd for dvloping a finit lmnt modl of lasr bam machining for slctd matrial and stady stat followd by th transint thrmal analysis is carrid on th sam modl in ordr to prdict th tmpratur distribution and hat affctd zon around th machind ara using finit lmnt analysis softwar. Indx Tr finit lmnt modl, titanium alloy, transint thrmal analysis, hat affctd zon. I. INTRODUCTION Lasr Bam Machining (LBM) is on of th unconvntional mthods of machining th matrials of highr hardnability charactristics. Convntional machining tnds to produc gratr forcs to act upon th substanc which may not b suitabl for th matrial and thus th LBM coms into play as it is indd mor associatd with th matrial proprtis such as th thrmal conductivity and spcific hat as wll as mlting and boiling tmpratur. Incrasing dmand for advancd difficult-to-procss matrials and th availability of high-powr lasrs hav stimulatd intrst in rsarch and dvlopmnt rlatd to lasr machining. As th lasr falls on to th surfac th un-rflctd light is absorbd by th surfac. Whn sufficint powr is achivd th surfac mlts and vaporizs. Th procss is difficult and complx du to th scattring and rflction losss at th machind surfac. Also th hat diffusion into th bulk matrial causs phas chang, mlting and vaporization. Dpnding upon th powr dnsity and th tim of bam, th mchanism progrsss from hat absorption to th mlting and vaporization. High intnsity of lasr bam is not rcommndd as it may caus th formation of plasma and dwindl th fficincy of th procss du to th scattring and absorption losss. Th rat of machining dpnds upon many factors and paramtrs such as th lasr powr, puls duration, spot diamtr and many othrs. Machining by lasr occurs whn th powr dnsity of th bam is gratr than what is lost by conduction, convction, and radiation, and morovr, th radiation must pntrat and b absorbd into th matrial. Th rlativly lowr mass for a givn strngth lvl and its rsistanc to th high tmpratur maks titanium an appropriat mtal to b usd in various filds majorly th arospac industry. It has bn usd to construct th front ngin parts and rotor blads as wll as th landing gar componnts of th aroplans. Titanium alloy 5553 is a rlativly nw mtal usd in th arospac sctor du to its outstanding proprtis. It coms undr th catgory of supr alloys which hav sublim hardnability and strngth charactristics. Titanium 5553 (Ti-5Al-5V-5Mo-3Cr) is a nar bta alloy which is radily hat-tratabl, gnrally wld abl, and has high strngths. Excllnt formability can b xpctd in th solution tratd condition. Bta alloys hav a good combination of proprtis for sht, havy sctions, fastnrs, and spring applications. II. LITERATURE J. W. Jung t al [1], prsnts th dformation rrors causd by thrmal ffcts in th lasr-assistd machin tool. Lasr assistd machin tool prfor th localizd hating and cutting procss simultanously. So, th hats gnratd by localizd hating procss as wll as th cutting procss ar conductd into cutting tool. In ordr to prdict dformation rrors, th hats from th two hat sourcs hav to b analysd simultanously and thrmal distortion hav to b calculatd. Th procdur for prdicting th thrmal distortion by lasr powr and cutting tmpratur had prsntd. Total procdur has prsntd in squnc of of thr stps. First stp, th commrcial softwar Sim dsignr was usd to analys tmpratur distribution of matrial rmoval plan by moving hat sourc. Scond stp, aftr dfining rsult of th analysis first stp, commrcial softwar AdvantEdg was usd to calculat th cutting tmpratur by modlling a simpl orthogonal cutting. Third stp, th commrcial softwar Simdsignr was usd to analys thrmal distortion by inputting th calculatd cutting tmpratur and forc by th scond stp. Th rsults can b usd to incras th cutting accuracy by compnsating thrmal distortion prior to lasr-assistd machining. Chithirai Pon Slvan M t al [2], prsnts a rviw on th conclusions of th various rsarch paprs availabl on lasr bam machining on th various proprtis that affct th quality of th procss such as hat affctd zon formd in th work-pic, lasr cut quality and why lasr bam machining is mor advancd than th othr machining procsss. Stwart and David t al [3], prsnts th microstructur and matrial proprtis of th workpic titanium This articl summarizs th xprimntal casting studis carrid out including castability, microstructur/proprty corrlation, and valuation of a 3155

2 bulkhad casting, proprty assssmnts, and manufacturability. In th prsnt rsarch work, a finit lmnt modl of a componnt is dvlopd using plan 55 axisymmtric lmnt in ANSYS. This modl is usd for furthr analysis i.. transint thrmal analysis in ordr to prdict th tmpratur distribution and hat affctd zon around th machind ara. III. TITANIUM 5553 ALLOY Th rlativly lowr mass for a givn strngth lvl and its rsistanc to th high tmpratur maks titanium an appropriat mtal to b usd in various filds majorly th arospac industry. It has bn usd to construct th front ngin parts and rotor blads as wll as th landing gar componnts of th aroplans. Titanium alloy 5553 is a rlativly nw mtal usd in th arospac sctor du to its outstanding proprtis. It coms undr th catgory of supr alloys which hav sublim hardnability and strngth charactristics. Titanium 5553 (Ti-5Al-5V-5Mo-3Cr) is a nar bta alloy which is radily hat-tratabl, gnrally wld abl, and has high strngths. Excllnt formability can b xpctd in th solution tratd condition. Bta alloys hav a good combination of proprtis for sht, havy sctions, fastnrs, and spring applications PROPERTIES Tabl I Proprtis of Ti 5553 ISSN: VALUE 1. Thrmal conductivity 5.8 ( Wm -1 K -1 ) 2. Spcific hat 550 ( JKg -1 K -1 ) 3. Dnsity 4670 (Kgm -3 ) 4. Ultimat tnsil strngth (MPa) 1159 Th rat of machining dpnds upon many factors and paramtrs such as th lasr powr, puls duration, spot diamtr and many othrs. Machining by lasr occurs whn th powr dnsity of th bam is gratr than what is lost by conduction, convction, and radiation, and morovr, th radiation must pntrat and b absorbd into th matrial. Th powr dnsity of th lasr bam, P d is givn by P d = 2L P / F t) Whr siz of th spot diamtr d s = F 1 P d = powr dnsity, W/cm 2 L p = lasr powr, W F 1 = focal lngth of lns, cm T = puls duration of lasr, s In prsnt analysis, th convction co-fficint of hat transfr, hat input and ambint tmpratur ar applid as boundary conditions. Th hat input basd on diffrnt lasr powrs ar calculatd. Tabl III Hat calculation for diffrnt boundary conditions valus Powr (W) Puls tim () Hat(W)(*10^7) Yild strngth 1055 (MPa) 6. Elongation prcntag (%) 9 7. Comprssiv strngth (MPa) Shar strngth (MPa) Tabl II Chmical composition of Ti Ti Ti Al V Mo Cr F 5553 Min Bas Max Bas V.RESULTS AND DISCUSSION ratur distribution occurs in axial way in all dirction and this tmpratur distributs along th nod by nod in a dcrasing mannr. Th first phas of th rsults includ th tmpratur variation of th substanc whn th lasr acts upon it and th scond includs th dath lmnt analysis rsults. Th blow givn Finit Elmnt Modls obtaind show th hat affctd zon for th matrial whn various hat input is applid whn changs in puls tim and powr occur. Ths rsults ar plottd on th graph against valus of tmpratur and othr variabls. IV.BOUNDARY CONDITIONS In prsnt analysis, th convction co-fficint of hat transfr, hat input and ambint tmpratur ar applid as boundary conditions. Th hat input basd on diffrnt lasr powrs ar calculatd as follows and it will b usd in analysis. 3156

3 From fig 3, it is infrrd that whn a powr of 250 W is applid on to th surfac for a puls tim of 0.6 milliscond a maximum tmpratur of 2005 K is achivd which dwindls to 681 K within 2 nods. Ths ANSYS rsults show th hat affctd zon vry clarly and this can b furthr shown in graphical format. Fig.1 Whn powr of 200 W and a puls tim of 0.2 milliscond is applid From fig 1, it is infrrd that whn a powr of 200 W is applid on to th titanium alloy surfac with a puls tim of about 0.2 milliscond, a maximum tmpratur of about is rachd and th nodal tmpratur can b asily diffrntiatd within th ANSYS rsults which ar furthr prsntd in th graphical format. Fig.4 Whn powr of 300 W and a puls tim of 0.6 milliscond is applid From fig 4, it is infrrd that whn a powr of 300 W is applid on to th surfac for a puls tim of 0.6 milliscond a maximum tmpratur of 2346 K is achivd which dwindls to 757 K within 2 nods. Ths ANSYS rsults show th hat affctd zon vry clarly and this can b furthr shown in graphical format as shown blow. Tabl IV ratur at diffrnt nods with variation in cntr distanc (for puls duration 0.4 ) Fig.2 Whn powr of 250 W and a puls tim of 0.4 milliscond is applid From fig 2, it is infrrd that whn a powr of 250 W is applid on to th surfac for a puls tim of 0.4 milliscond a maximum tmpratur of about K is achivd which furthr st down to K whn raching th third nod. cntr distanc (mm) ratur (p=250w) ratur (P=200W) ratur (P=300W) Th dtaild graphical rprsntation for vry cas is plottd blow. Th tmpratur variation for subsqunt cntr distanc is notd down for diffrnt powr of lasr for a puls duration of 0.4 milliscond. Th maximum tmpratur varis from K to K as w mov from cntr distanc to th othr nods. Fig.3 Whn powr of 250 W and a puls tim of 0.6 milliscond is applid 3157

4 milliscond is th most suitabl choic as it radily mlts th Tabl VI ratur valus at diffrnt nods undr puls duration variation whn P=200W (t=0.2) (t=0.6) Fig.5 ratur vs cntr distanc (puls duration =0.4) Fig 7 ratur valus at diffrnt nods undr puls duration variation at P=200 W Fig.6 ratur valus at diffrnt nods undr puls duration variation at P=250 W From fig 6, it can b infrrd that th tmpratur variation of a lasr of powr 250 W is shown with variation in dcrass from 5414 to 870 as shown in th graph which givs us an ida that a lasr of puls duration of 0.4 milliscond is th most suitabl choic as it radily mlts th Tabl V ratur valus at diffrnt nods undr puls duration variation whn P=250W (t=0.2) (t=0.6) From fig 8, it can b infrrd that th tmpratur variation of a lasr of powr 300 W is shown with variation in dcrass from to as shown in th graph which givs us an ida that a lasr of puls duration of 0.4 milliscond is th most suitabl choic as it radily mlts th Tabl VII ratur valus at diffrnt nods undr puls duration variation whn P=300 W (t=0.2) (t=0.6) From fig 7, it can b infrrd that th tmpratur variation of a lasr of powr 200 W is shown with variation in dcrass from to as shown in th graph which givs us an ida that a lasr of puls duration of

5 Aashish Mallik: H is prsntly pursuing Mchanical Enginring ( Final India. His aras of intrst is thrmal scincs and finit lmnt mthods. Gansh Kharl: H is prsntly pursuing Mchanical Enginring (Final yar) in Sri Vnkatswara collg of Enginring & Tchnology, Chittoor, A.P, India. His aras of intrst ar manufacturing tchnology and finit lmnt mthods. A. Kumara Swamy: H is prsntly pursuing Mchanical Enginring ( Final India. His aras of intrst ar manufacturing tchnology. E. Ranjith Kumar: H is prsntly pursuing Mchanical Enginring ( Final India. His aras of intrst ar mchanics of solids and finit lmnt mthods. Fig 8 ratur valus at diffrnt nods undr puls duration variation at P=300 W VI CONCLUSION Th analysis of th givn alloy of titanium machinabl with a CO 2 lasr of powr varying btwn W as pr suitabl paramtrs is accomplishd with th hlp of finit lmnt analysis. Th hat affctd zon for th givn matrial is calculatd for diffrnt lasr intnsity valus. Th boundary conditions takn wr ascrtaind to b corrct upon gtting dsirabl rsults from softwar analysis. REFERENCES 1. J. W. Jung, C. M. L Cutting ratur and Lasr Bam ratur Effcts On Cutting Tool Dformation in Lasr assistd Machining Procdings of th Intrnational Multi Confrnc of Enginrs and Computr Scintists 2009 Vol III MECS 2009, March 18-20, 2009, Hong Kong 2. Chithirai Pon Slvan M, Nthri Rammohan and Sachidananda HK Lasr Bam Machining: A Litratur Rviw on Hat affctd Zons, Cut Quality and Comparativ Study Europan Journal of Advancs in Enginring and Tchnology, 2015, 2(10): Stwart Vck and David L Rodny Boyr and Robrt Briggs Th castability of titanium 5553 alloy advancd matrials and procsss, Octobr 2004, pp Shoujin Sun and Milan Brandt Lasr Bam Machining chaptr 2. May 2013, pp Black, S.A.J. Livingston, K.L. Chua A Lasr bam machining databas for cutting of cramic til Journal of Matrials Procssing Tchnology 84 (1998) pp Johan Mijr lasr bam machining, stat of art and nw oppurtunitis Journal of Matrials Procssing Tchnology 149 (2004) pp Vijay K. Jain, Advancd Machining Procss Allid Publishrs Pvt. Ltd., 24 th Edition, 2014, pp Hassan El-Hofy, Advancd Machining Procss non-traditional and hybrid machining procsss McGraw Hill Pvt. Ltd., 7 th Edition, 2004, pp B.S Grwal Highr Enginring Mathmatics Khanna publishrs, 37 th dition pp D Vnkata Krishna: H is working as assistant profssor in th dpartmnt of mchanical nginring, Sri Vnkatswara collg of Enginring & Tchnology, Chittoor, A.P, India. H pursud his bachlor dgr in Mchanical nginring from Jawaharlal Nhru Tchnological Univrsity of Ananatapur, Pulivndula and Post graduation in computr Intgratd manufacturing from PSG Collg of Tchnology, Coimbator (Anna Univrsity, Chnnai). His ara of intrst ar machin tools and thrmal scincs. H has publishd ovr 6 paprs in wll rputd journals in th ara of CNC Machin tools. 3159